Acid-base Approach Research Articles

IL/MIL-101-NH2 heterogeneous catalyst prepared by acid-base self-assembly for hydrodeoxygenation of 2,5-tetrahydrofurandicarboxylic acid to adipic acid

Bio-based route for preparing adipic acid (AA) from 5-hydroxymethylfurfural is the direction for achieving green and sustainable AA production. In light of the challenges, such as corrosion and difficulties in recycling of I- containing homogeneous catalyst, large amount, high cost, and significant mass transfer resistance of ionic liquid (IL) catalyst, encountered in the current hydrodeoxygenation of 2,5-tetrahydrofurandicarboxylic acid (THFDCA) to AA process. Herein, 1-sulfobutyl-3-methylimidazolium iodide IL ([HSO3-b-mim]·I) was used to functionalize MIL-101-NH2 through acid-base self-assembly approach, hence, a heterogeneous catalyst, IL/MIL-101-NH2 was designed and applied in the hydrodeoxygenation of THFDCA to bio-based AA for the first time. When reacted at 180 °C for 2 h, the THFDCA conversion and AA yield were 100 % and 99.9 %, respectively. Moreover, IL/MIL-101-NH2 exhibited remarkable stability and could be reused multiple times with minimal loss in activity. XRD, SEM, FT-IR, BET, XPS, and TG results revealed that the functionalization process involved the reaction between HSO3 in the IL and NH2 in MIL-101-NH2, forming a salt that chemically bonded the IL to MIL-101-NH2, thereby enhancing stability. The excellent hydrodeoxygenation activity was attributed to the synergistic effect of the Lewis acid site (Cr3+) and the Lewis base nucleophilic site (I-) within IL/MIL-101-NH2.

Enhanced proton transfer in proton exchange membrane fuel cells via novel nanocomposite membrane incorporating (3-Mercaptopropyl)trimethoxysilane-graphene oxide and basic amino ligands: A synergistic acid-base approach

A nanocomposite polymer electrolyte membrane (MGC) was synthesized by blending MPTS (HS(CH2)3Si(OCH3)3) and graphene oxide (GO) nanosheets at varying weight ratios (91.5 to 9.5, respectively) for proton exchange membrane fuel cell (PEMFC) applications. By covalently modifying the GO support with MPTS through a silane modification process, the acidic MGC matrix is formed. The blending process, with ultrasonication and vigorous stirring, initiates two significant reactions in reactive MPTS: first, the conversion of methoxy groups (Si–OCH3) to silanols (Si-OH); second, the potential condensation of silanol groups to form siloxane bonds (Si–O–Si), followed by oxidation of sulfhydryl groups to sulfonic acid (-SO3H) groups by hydrogen peroxide. The resulting -SO3H groups connected to the siloxane network (Si-O-Si) adjacent to the GO. Two basic amino ligands – dopamine, and aminopropyl trimethoxysilane (APTES) were incorporated into the MGC matrix to establish acid-base pairs, promoting swift proton transport. These additions, at weight ratios of (0.5, 1, 2, and 7) wt%, synergistically contributed to the MGC matrix, forming effective proton channels. Various analytical techniques, including field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS), were employed to assess the impact of functionalized basic amino groups on the MGC matrix. Notably, the MGC membrane containing 2 wt% of PDA as basic amino ligands exhibited optimal performance, showcasing an in-plane proton conductivity of 115.10 mS cm-1 under fully hydrated conditions at 90 °C, and the maximum power density (MPD) of 170.74 mW cm-2 with a current density of 1051.46 mA cm-2 at 60 °C and 100 % relative humidity (RH). In contrast, the MGC membrane, devoid of amino ligands, exhibited a comparatively low in-plane conductivity of 44.32 mS cm⁻¹ under identical conditions at 90 °C. Additionally, it recorded the MPD of 48.5 mW cm⁻², corresponding to a current density of 313.25 mA cm⁻² at 60 °C and 100 % RH. This study introduces an innovative approach for developing high-performance nanocomposite membranes for PEMs and related applications.

Cyanoacetamide co-sensitizers DY-1 and DY-2: Unveiling a promising path to highly efficient photovoltaic devices

This paper presents a novel approach for enhancing the efficiency of dye-sensitized solar cells (DSSCs) through the co-sensitization of cyanoacetamide-based dyes DY-1 and DY-2 with N3 dye. The synthesis and characterization of DY-1 and DY-2 co-sensitizers are described and their potential applications in photovoltaic devices are investigated. The absorption properties of DY-1 and DY-2 were analyzed, revealing their efficient light absorption in the visible range. The co-sensitization of DY-1-2 with N3 dye demonstrated a significant enhancement in photovoltaic efficiency, ranging from 7.40 % to 7.92 %. The reasons for this efficiency enhancement were thoroughly analyzed and attributed to several factors. First, the combination of DY-1-2 with the N3 dye led to a broader light absorption spectrum, enabling more efficient utilization of incident photons. Additionally, co-sensitization facilitates efficient charge separation and injection processes, contributing to improved photocurrent. The acid-base co-sensitization approach further enhances the overall efficiency by maximizing the charge transfer and coverage on the semiconductor surface. This study sheds light on the development of novel sensitizers to enhance the performance of DSSCs, and the findings contribute to the advancement of photovoltaic devices.

Physico-chemical characterization of acid base disorders in patients with COVID-19: A cohort study

BACKGROUND Acid-base imbalance has been poorly described in patients with coronavirus disease 2019 (COVID-19). Study by the quantitative acid-base approach may be able to account for minor changes in ion distribution that may have been overlooked using traditional acid-base analysis techniques. In a cohort of critically ill COVID-19 patients, we looked for an association between metabolic acidosis surrogates and worse clinical outcomes, such as mortality, renal dialysis, and length of hospital stay. AIM To describe the acid-base disorders of critically ill COVID-19 patients using Stewart’s approach, associating its variables with poor outcomes. METHODS This study pertained to a retrospective cohort comprised of adult patients who experienced an intensive care unit stay exceeding 4 days and who were diagnosed with severe acute respiratory syndrome coronavirus 2 infection through a positive polymerase chain reaction analysis of a nasal swab and typical pulmonary involvement observed in chest computed tomography scan. Laboratory and clinical data were obtained from electronic records. Categorical variables were compared using Fisher’s exact test. Continuous data were presented as median and interquartile range. The Mann-Whitney U test was used for comparisons. RESULTS In total, 211 patients were analyzed. The mortality rate was 13.7%. Overall, 149 patients (70.6%) presented with alkalosis, 28 patients (13.3%) had acidosis, and the remaining 34 patients (16.2%) had a normal arterial pondus hydrogenii. Of those presenting with acidosis, most had a low apparent strong ion difference (SID) (20 patients, 9.5%). Within the group with alkalosis, 128 patients (61.0%) had respiratory origin. The non-survivors were older, had more comorbidities, and had higher Charlson’s and simplified acute physiology score 3. We did not find severe acid-base imbalance in this population. The analyzed Stewart’s variables (effective SID, apparent SID, and strong ion gap and the effect of albumin, lactate, phosphorus, and chloride) were not different between the groups. CONCLUSION Alkalemia is prevalent in COVID-19 patients. Although we did not find an association between acid-base variables and mortality, the use of Stewart’s methodology may provide insights into this severe disease.

Alactic base excess (ABE): a novel internal milieu parameter-its concept and clinical importance.

Inspired by the Stewart-Figge acid-base approach, Gattinoni et al. recently introduced a new internal milieu parameter known as alactic base excess (ABE). The authors defined ABE as the sum of lactate and standard base excess. In the context of sepsis, ABE has been proposed as a valuable marker to discern between metabolic acidosis resulting from the accumulation of lactate and the retention of fixed acids, which can occur in cases of renal failure. Multiple studies have demonstrated that a negative ABE value (<-3mmol/L) represents an early marker of renal dysfunction, and significantly correlates with higher mortality rates in septic patients. In conclusion, ABE is a simple and useful parameter that can be used to better interpret a patient's acid-base status, assess renal function, and general prognosis in sepsis. By incorporating ABE into clinical practice, healthcare professionals can enhance their understanding of the complex acid-base imbalances in their patients and tailor more individualized, effective treatment plans.

Facile preparation of porphyrin@g-C3N4/Ag nanocomposite for improved photocatalytic degradation of organic dyes in aqueous solution

In the quest of improving the photocatalytic efficiency of photocatalysts, the combination of two and more semiconductors recently has garnered significant attention among scientists in the field. The doping of conductive metals is also an effective pathway to improve photocatalytic performance by avoiding electron/hole pair recombination and enhancing photon energy absorption. This work presented a design and fabrication of porphyrin@g-C3N4/Ag nanocomposite using acid-base neutralization-induced self-assembly approach from monomeric porphyrin and g-C3N4/Ag material. g-C3N4/Ag material was synthesized by a green reductant of Cleistocalyx operculatus leaf extract. Electron scanning microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, and UV–vis spectrometer were utilized to analyse the properties of the prepared materials. The prepared porphyrin@g-C3N4/Ag nanocomposite showed well integration of porphyrin nanostructures on the g-C3N4/Ag's surface, in which porphyrin nanofiber was of the diameter in nanoscales and the length of several micrometers, and Ag NPs had an average particle size of less than 20 nm. The photocatalytic behavior of the resultant nanocomposite was tested for the degradation of Rhodamine B dye, which exhibited a remarkable RhB photodegrading percentage. The possible mechanism for photocatalysis of the porphyrin@g-C3N4/Ag nanocomposite toward Rhodamine B dye was also proposed and discussed.

Enhanced biopharmaceutical performance of brick dust molecule nilotinib via stabilized amorphous nanosuspension using a facile acid-base neutralization approach.

"Brick dust" compounds have high lattice energy as manifested by the poor aqueous solubility and suboptimal bioavailability. Nilotinib being a weakly basic brick dust molecule exhibits erratic and limited absorption during gastrointestinal transit, attributed to pre-absorptive factors like pH-dependent solubility, poor dissolution kinetics, and post-absorptive factors including P-gp-mediated drug efflux. In our study, these problems are addressed holistically by the successful fabrication of amorphous nanosuspension by an acid-base neutralization approach. The nanosuspension was obtained via rapid precipitation of nilotinib in an amorphous form and the generated in situ sodium chloride salt assisted in stabilizing the drug-loaded nanosuspension in a cage of salt and micellar stabilizer. Soluplus® and hypromellose acetate succinate (HPMCAS) were employed as a novel combination of stabilizers. Systematic optimization was carried out by employing the I-optimal method using Design Expert®software with a concentration of HPMCAS and Soluplus®as independent variables and evaluating them for responses viz particle size, polydispersity index (PDI), and zeta potential. The resultant nanosuspension showed a mean particle size of 130.5 ± 1.22nm with a PDI value of 0.27 ± 0.01, and a zeta potential of - 5.21 ± 0.91mV. The nanosuspension was further characterized for morphology, dissolution, and in vivo pharmacokinetics study. X-ray powder diffraction study of the nano-formulation displayed a halo pattern revealing the amorphous form. Stability studies showed that the nanosuspension remained stable at 40°C ± 2°C and 75% RH ± 5% RH for a period of three months. In vitro drug release and solubility study showed threefold and 36-fold enhancement in dissolution and solubility of the nanosuspension. Furthermore, an in vivo pharmacokinetic study in Sprague-Dawley rats following oral administration displayed a 1.46-fold enhancement in the relative bioavailability of the nanosuspension in contrast to neat nilotinib.

Silane coupling agent impact on surface features of modification of basalt fibers and the rheological properties of basalt fiber reinforced asphalt

Rheological properties of fiber reinforced asphalt (FRA) can be significantly influenced by the surface properties of fibers. Modified basalt fibers are emerging materials used to enhance the performance of FRA. Silane coupling agents (SCAs) make it possible to introduce versatile surface features to basalt fibers (BFs). Six typical SCAs were tested and evaluated for modifications on the rheological properties of BF reinforced asphalt at different high-level temperatures. The specific characteristics of each modified BF was measured by dynamic surface tension meter, denoted as surface energy components (SFEC), calculated using two distinct methods, OWRK (dispersive-polar approach) and vOCG (acid-base approach). The semi-quantitative correlation between SFEC based on each method and rheological properties with regard to temperature response were detailed. Study results show that Van de Waals interaction and acid-base interaction is more suitable to describe the interaction between asphalt and basalt fibers, and the interaction mechanism changes when temperature increases. Our research provides a guidance in the modification of SCAs when used in combination with mineral fillers to improve the overall performance of asphalt mixtures. Additionally, a novel SCA carrying long chain alkanes (UP312) shows high potential for modifying mineral fillers with excellent water resistance and improvement in the rutting resistance of asphalt concrete.

Physicochemical Analysis of Mixed Venous and Arterial Blood Acid-Base State in Horses at Core Temperature during and after Moderate-Intensity Exercise.

Simple SummaryThe purposes of the present study were to determine the effect of core body temperature on acid-base variables and determine the origins of acid-base changes in the arterial and mixed venous blood of horses during exercise and recovery. Moderate intensity exercise resulted in an increase in body temperature that, in addition to exercise, affected acid-base status and gas partial pressures. Moderate intensity exercise resulted in a mild alkalosis that had markedly different origins in arterial blood than in mixed venous blood, and this was affected by the increase in core temperature during exercise and its resolution during recovery. In order to fully understand how acid-base status changes during exercise and recovery, it is importance to quantify the changes in both arterial and mixed venous blood, with adjustment to core temperature. Acid-base assessments using jugular vein blood samples are limited in comparison.The present study determined the independent contributions of temperature, strong ion difference ([SID]), total weak acid concentration ([Atot]) and PCO2 to changes in arterial and mixed venous [H+] and total carbon dioxide concentration ([TCO2]) during 37 min of moderate intensity exercise (~50% of heart rate max) and the first 60 min of recovery. Six horses were fitted with indwelling carotid and pulmonary artery (PA) catheters, had PA temperature measured, and had blood samples withdrawn for immediate analysis of plasma ion and gas concentrations. The increase in core temperature during exercise (+4.5 °C; p < 0.001) significantly (p < 0.05) increased PO2, PCO2, and [H+], but without a significant effect on [TCO2] (p > 0.01). The physicochemical acid-base approach was used to determine contributions of independent variables (except temperature) to the changes in [H+] and [TCO2]. In both arterial and venous blood, there was no acidosis during exercise and recovery despite significant (p < 0.05) increases in [lactate] and in venous PCO2. In arterial blood plasma, a mild alkalosis with exercise was due to primarily to a decrease in PCO2 (p < 0.05) and an increase in [SID] (p < 0.1). In venous blood plasma, a near absence of change in [H+] was due to the acidifying effects of increased PCO2 (p < 0.01) being offset by the alkalizing effects of increased [SID] (p < 0.05). The effect of temperature on PO2 (p < 0.001) resulted in an increased arterio-venous PO2 difference (p < 0.001) that would facilitate O2 transfer to contracting muscle. The simultaneous changes in the PCO2 and the concentrations of the other independent acid-base variables (contributions from individual strong and weak ions as manifest in [SID] and [Atot]) show complex, multilevel control of acid-base states in horses performing even moderate intensity exercise. Correction of acid-base variables to core body temperature presents a markedly different physiological response to exercise than that provided by variables measured and presented at an instrument temperature of 37 °C.

MnCoP hollow nanocubes as novel electrode material for asymmetric supercapacitors

• Hierarchical nanosheet-based MnCoP hollow nanocubes were synthesized and characterized. • MnCoP has uniform morphology, electrical conductivity, structural stability and large surface area. • As a battery-type positive electrode, MnCoP showed a maximum capacity of 879 Cg −1 at 2 Ag −1 . • Superior cycling stability of 94.4% capacitance retention after 6,000 cycles achieved. • Maximum energy density of 66.98 Wh Kg −1 and power density of 16466 W Kg −1 were found. Fabrication of novel and efficient electrodes for green and renewable hybrid energy storage systems is an effective approach to deal with energy crisis. In this work, hierarchical nanosheet-based MnCoP hollow nanocubes electrode with the battery type feature has been successfully synthesized by a simple hard and soft acid-base (HSAB) approach followed by a heat treatment. By taking advantage of the remarkable merits including uniform morphology, electrical conductivity, structural stability, large surface area as well as the battery type feature, the nanosheet-based MnCoP hollow nanocubes electrode exhibits enhanced electrochemical performance with high specific capacity of 879C g −1 at 2 A g −1 excellent cycling stability of 94.4% capacity retention after 6,000 cycles, and maximum energy and power density of 66.98 Wh Kg −1 and 16446 W Kg −1 , respectively.

Isolation of natural caffeine from liptonâ„¢ black tea through acid-base liquid-liquid extraction approach, its medical significance and its characterization by thin layer chromatography and IR analysis

To isolate the caffeine from Liptonâ„¢ Black Tea Brand, a sequence of practices was applied. An Acid-Base Liquid-Liquid Extraction approach carried out to force the caffeine to be isolated in upper organic layer as extractant. By this method, first caffeine was isolated from tea bags through passing different steps of extraction, then caffeine was isolated from tea with the use of both Solid-Liquid approach as well as liquid-liquid extraction approach. A product of 0.05 g of pure caffeine was obtained giving the percentage yield or percent recovery of 1.22%. Calculated percent recovery was 1.2 %, this percentage yield clarified that in this tea brand, very small caffeine is investigated, this deduces a significant loss of product throughout the procedure which are due to formation of emulsions and not due to washing thoroughly with DCM to extract maximum yield. It is also significant to be considered that reactions of precursor with solvent pair may not be completed, so 100% yield is not conceivable. Due to much transfers in all processes, this loss might be occurred. Due to much transfers in all processes, this loss might be occurred that’s why repeated the process three times again. It is also revealed that as much water was added which decreased the concentration of Caffeine. On analysis with IR, Peak at f=3000Hz indicates the presence of -NH2 and -CONH2 groups while the peaks at f=1600 Hz and f=1750 Hz indicates the presence of alkene portion of the caffeine molecule which concluded that Caffeine is a purine base. Â

Friction at nanopillared polymer surfaces beyond Amontons’ laws: Stick-slip amplitude coefficient (SSAC) and multiparametric nanotribological properties

Frictional and nanomechanical properties of nanostructured polymer surfaces are important to their technological and biomedical applications. In this work, poly(ethylene terephthalate) (PET) surfaces with a periodic distribution of well-defined nanopillars were fabricated through an anodization/embossing process. The apparent surface energy of the nanopillared surfaces was evaluated using the Fowkes acid-base approach, and the surface morphology was characterized using scanning electron microscope (SEM) and atomic force microscope (AFM). The normal and lateral forces between a silica microparticle and these surfaces were quantified using colloidal probe atomic force microscopy (CP-AFM). The friction-load relationship followed Amonton’s first law, and the friction coefficient appeared to scale linearly with the nanopillar height. Furthermore, all the nanopillared surfaces showed pronounced frictional instabilities compared to the smooth sliding friction loop on the flat control. Performing the stick–slip amplitude coefficient (SSAC) analysis, we found a correlation between the frictional instabilities and the nanopillars density, pull-off force and work of adhesion. We have summarised the dependence of the nanotribological properties on such nanopillared surfaces on five relevant parameters, i.e. pull-off force fp, Amontons’ friction coefficient μ, RMS roughness Rq, stick–slip amplitude friction coefficient SSAC, and work of adhesion between the substrate and water Wadh in a radar chart. Whilst demonstrating the complexity of the frictional behaviour of nanopillared polymer surfaces, our results show that analyses of multiparametric nanotribological properties of nanostructured surfaces should go beyond classic Amontons’ laws, with the SSAC more representative of the frictional properties compared to the friction coefficient.

Poly(ethylene terephthalate)–Clay Nanocomposite Multifilament Yarn: Physical and Thermal Properties

Poly(ethylene terephthalate)/clay nanocomposite multifilament yarn was manufactured by conventional masterbatch approach. Poly(butylene terephthalate) was used as a carrier polymer in masterbatch steps. The masterbatches were diluted into pilot melt spinning machine and subsequently drawn with 2.65 ratios to prepare fully oriented yarn. The degree of dispersion in nanocomposite fibers was analyzed by X-ray diffractometry and scanning electron microscopy. Even though the addition of nanoclay reduced mechanical properties of nanocomposite fibers, dimensional stability could be improved at certain clay contents. The flammability properties were sufficiently improved, and no significant changes were observed with increasing clay content. The main novelty of this paper is the development of a proper approach for the selection of optimum carrier polymer for nanoclay in masterbatch preparation, as well as proper nanoclay for desired polymers. The acid-base approach is used in evaluating the surface free energy of commercial nanoclay and calculation the total interaction energies between polymer and clay surfaces. Such an approach gives adequate information about polymer-clay compatibility and provides a useful tool in the selection of optimum carrier polymer, as well as proper nanoclay for the desired polymer during masterbatch preparations.

Strategy of selecting solvent systems for spherical agglomeration by the Lifshitz-van der Waals acid-base approach

A strategy for rationally selecting solvent systems of spherical agglomeration is proposed for the first time. It emphasizes that followed by crystallization and phase separation, spherical agglomeration can be achieved only when the solvent system can induce wetting and adhesion which are estimated by the Lifshitz-van der Waals acid-base approach. Especially for wettability of bridging liquid, solvent and anti-solvent, the strategy indicates that it is of great importance for a successful solvent system. Valid systems therefore are selected in the first place while invalid ones are removed effectively according to the wettability difference. Based on the strategy, valid solvent systems for cefotaxime sodium and benzoic acid spherical agglomeration were selected successfully from 720 and 2184 systems respectively without missing the reported systems. The strategy also predicted no valid systems for potassium chloride, maltitol and trisodium phosphate in the given solvent combinations, which agreed with the experiment results.

FLUXES WITH DECREASED VISCOSITY AFTER REFLOW FOR FLIP-CHIP AND SIP ASSEMBLY

Abstract A series of flux systems have been developed which would result in a reduced viscosity after reflow. This enables a high viscosity, high tack flux to be used to secure components at the component placement and reflow stage, but ends up with a low viscosity flux residue after reflow, thus facilitating the flux residue to be cleaned. A technique for forming such special fluxes is to establish a temporary association force within the materials themselves, such as an acid-base association. This kind of association force can increase the apparent molecular weight and cause material viscosity to increase. After a heating process, one of the critical ingredients was evaporated, thus eliminating the association force, causing a decrease in the apparent molecular weight, and consequently a decrease in viscosity or an increase in mobility. The evaporation of one ingredient can be the result of one ingredient having a lower boiling point, or the decomposition of one ingredient during heating. A strong association force is desired to allow this acid-base combination approach to work. In this work, the volatile ingredient approach was less effective than a decomposable ingredient approach, presumably due to the formation of a bigger association cluster from the decomposable ingredient. Accordingly, the decomposable ingredient was the best approach to lower flux viscosity after reflow.

Wettability and Interfacial Properties of Carbon Fiber and Poly(ether ether ketone) Fiber Hybrid Composite.

Studies on carbon fiber (CF)/poly(ether ether ketone) (PEEK) fiber hybrid textiles were initiated several decades ago because their flexibility and conformability make them a promising alternative to traditional prepregs. The adhesion between the CFs and PEEK is mostly controlled by their inherent surface properties and mutual wettability. However, details of these properties remain largely unknown, especially those of PEEK. Therefore, to determine the surface and interfacial properties of these fibers, we performed a comprehensive study and characterized their surface topography (atomic force microscopy, scanning electron microscopy), surface chemistry [X-ray photoelectron spectrometry (XPS), acid-base titration], surface energies (wetting tests, acid-base approach), and interfacial mechanical properties [droplet test, interfacial shear strength (IFSS)]. These experiments were complemented by a theoretical approach to the prediction of the surface energy components (parachor) and contact angles of PEEK. We found good agreement between the results obtained by XPS and wetting tests (base-to-acid surface energy component ratio), as well as between the predicted and measured surface energy and contact angles. The results highlight the consistency and reliability of the proposed methodology. We found that both CFs and PEEK fibers appear to be smooth at the nanoscale and have large dispersive and basic surface energy components. The IFSS of CF/PEEK is significantly higher (44.87 ± 5.76 MPa) compared to that of other thermoplastic systems. The findings not only demonstrate the potential of CF/PEEK hybrid textiles but also emphasize the need to further increase the compatibility between CFs and PEEK fibers by increasing the acidic component of CF surfaces. Surface treatments and the design of a suitable sizing are potential methods to achieve this objective in future studies.

Crystallization and grain growth regulation through Lewis acid-base adduct formation in hot cast perovskite-based solar cells

The precise control of perovskite crystallization process that could provide smooth films with large grains is a prerequisite for solar cell fabrication to achieve higher efficiencies. To regulate this crystallization process and to achieve it multiple times remains a humongous challenge. This process has been reproducibly demonstrated here through efficient molecular exchange via a Lewis acid-base adduct formation. In this work, a Lewis acid-base adduct approach in concurrence with hot casting technique was employed to efficiently control the perovskite crystallization by judiciously adding dimethyl sulfoxide (DMSO) to a precursor solution of lead iodide (PbI 2 ) and methyl ammonium chloride (MACl) in dimethylformamide (DMF). High quality perovskite films were fabricated by precisely controlling the volume of DMSO which resulted in low recombination rate and which had better light harvesting ability. Uniform films of MAPbCl x I 3-x having large grain size were formed reproducibly on addition of 1.5 equivalents (eq.) DMSO to the precursor solution. Perovskite solar cells fabricated using this solution resulted in maximum power conversion efficiency (PCE) of 14.11% with enhanced stability as compared to the reduced PCE values obtained with other DMSO ratios and pure DMF solution cast films. • Hot casting using Lewis acid-base approach resulted in large grain perovskite. • 1.5 equivalents of Lewis base (DMSO) gave largest grain size and smooth film. • A power conversion efficiency >14% achieved in inverted perovskite solar cell. • This method also improved the overall stability of the solar cells.

A simplified quantitative acid-base approach for patients with acute respiratory diseases.

The Stewart-Figge acid-base model has been criticized for being mathematically complex. We aimed to develop simpler formalisms, which can be used at the bedside. The following simplifications were used: (1) [Ca2+] and [Mg2+] are replaced by their mid-reference concentrations (2) pH is set to 7.4. In the new model [SIDa] is replaced by its adjusted form, [SIDa, adj] = [Na+] + [K+] - [Cl-] + 6.5 and [SIG] is replaced by "bicarbonate gap", [BICgap] = [SIDa, adj] - (0.28⋅[Albumin]) - (1.82⋅[Phosphatei])- [HCO3̄]. The diagnostic performance of the model was tested in 210 patients with acute respiratory diseases and 17 healthy volunteers. [BICgap] was also compared to albumin-corrected anion gap ([AGc]). The concordant correlation coefficient between [SIDa, adj] and [SIDa] and between [BICgap] and [SIG] was 0.98 in both comparisons. The mean bias (limits of agreement) of [SIDa, adj] - [SIDa] and of [BICgap] - [SIG] were 0.53meq/l (- 0.46 to 1.53) and 0.50meq/l (- 0.70 to 1.70), respectively. A [SIDa, adj] < 50.4meq/l had an accuracy of 0.995 (p < 0.001) for the diagnosis of strong ion (SI) acidosis, while a [SIDa, adj] > 52.5meq/l had an accuracy of 0.997 (p < 0.001) for the diagnosis of SI alkalosis. A [BICgap] > 11.6meq/l predicted unmeasured ion (UI) acidosis with an accuracy of 0.997 (p < 0.001), while an [AGc] > 19.88meq/l predicted UI acidosis with an accuracy of 0.994 (p < 0.001). The "[BICgap] model" is a reliable tool for the assessment of acid-base disorders in patients with acute respiratory diseases. [BICgap] is not inferior to [AGc] in the diagnosis of UI acidosis.

Design and mechanism of the formation of spherical KCl particles using cooling crystallization without additives

Potassium chloride crystals are cubic, which often leads to caking and greatly limits their applications. This caking can be overcome by modifying the crystal shape toward sphericity. Spherical particles have a high anti-caking ability and flowability. In this work, spherical KCl particles were prepared using a simple cooling crystallization process designed to function without additives. Among the four main processes in the crystallization of spherical particles, i.e., nucleation, growth, agglomeration, and attrition, agglomeration is the greatest contributor to the formation of spherical KCl particles, which were prepared following the principle that the adhesion force must be larger than the dispersion force. The adhesion free energy between KCl particles and solvents (i.e., water, n-hexane, formamide, diazomethane, methanol, ethanol, ethyl acetate, ethylene glycol, and dimethyl sulfoxide) was calculated using the Lifshitz–van der Waals acid–base approach, and water was found to be the most appropriate solvent because of its attractive interaction with the crystals. According to the relationship between the adhesion force and dispersion forces, we found that the stirring rate should be lower than 1300 rpm. Additionally, the effects of stirring rate and cooling rate on the KCl products were investigated and optimized, and the optimal conditions were found to be 400–500 rpm and 10–15 min/°C, respectively. All of the spherical KCl products prepared under the optimal conditions show a better morphology, flowability, and anti-caking performance than the original crystals.

A Lewis acid-base chemistry approach towards narrow bandgap dye molecules

Although it usually involves troublesome and time-consuming synthesis work, molecular structure tailoring has been the mainstream tool to adjust the optical absorption and bandgap of organic semiconductors. Herein, we provided a convenient and feasible method to prepare narrow bandgap small-molecule semiconductors by Lewis acid-base chemistry and the optical absorption was adjusted by the stoichiometry of Lewis acid-base reactions. In this work, three pyridine capped diketopyrrolopyrrole (DPP) molecules, i.e., DPPPy-Ph-F, DPPPy-Ph-3F, and DPPPy-Py-F, with medium bandgap were synthesized to coordinate with Lewis acid of B(C6F5)3 (BCF). By coordinating with BCF, as demonstrated by 1H, 19F, and 11B NMR spectra, the bandgaps of these DPP molecules were depressed largely. For DPPPy-Ph-F, with two pyridine units flanking symmetrically, 2 eq of BCF converted the two pyridine nitrogens stoichiometrically to Lewis acid adducts, along with absorption bands red-shifted and bandgap depressed (1.89 vs. 1.80 eV). For DPPPy-Ph-3F, with two pyridine units flanked and trifluorobenzene capped, adding 2 eq of BCF was unable to convert the two pyridine nitrogens to BCF adducts completely, due to the strong electron-drawing ability of trifluorobenzene substituent on pyridine, reducing its basicity. After adding excess BCF to coordinate with nitrogens, the bandgaps of DPPPy-Ph-3F also decreased from 1.92 eV to 1.84 eV. For DPPPy-Py-F, with four pyridine units flanked, 4 eq of BCF were required to bind the pyridine nitrogens. Accordingly, the red-shift of absorption bands and the depression of optical bandgaps (1.96 vs. 1.75 eV) for DPPPy-Py-F were most striking among the three molecules.